Management of Ileal Neuroendocrine Tumors with Liver Metastases

Relation between WHO Classification and Location- and Functionality-Based Classifications of Neuroendocrine Neoplasms of the Digestive Tract

Practice of neuroendocrine neoplasms (NENs) of the digestive tract, which comprise of a highly diverse group of tumors with a rising incidence, faces multiple biological, diagnostic, and therapeutic issues. Part of these issues is due to misuse and misinterpretation of the classification and terminology of NENs of the digestive tract, which make it increasingly challenging to evaluate and compare the literature. For instance, grade 3 neuroendocrine tumors (NETs) are frequently referred to as neuroendocrine carcinomas (NECs) and vice versa, while NECs are, by definition, high grade and therefore constitute a separate entity from NETs. Moreover, the term NET is regularly misused to describe NENs in general, and NETs are frequently referred to as benign, while they should always be considered malignancies as they do have metastatic potential. To prevent misconceptions in future NEN-related research, we reviewed the most recent terminology used to classify NENs of the digestive tract and created an overview that combines the classification of these NENs according to the World Health Organization (WHO) with location- and functionality-based classifications. This overview may help clinicians and researchers in understanding the current literature and could serve as a guide in the clinic as well as for writing future studies on NENs of the digestive tract. In this way, we aim for the universal use of terminology, thereby providing an efficient foundation for future NEN-related research.

Management of Small Bowel Neuroendocrine Tumours: 10 Years' Experience at a Tertiary Referral Centre

BACKGROUND

Neuroendocrine tumours (NET) arising from the small bowel are clinically challenging and are often diagnosed at advanced stages. Disease control with surgery alone can be demanding. Multimodal treatment concepts integrating surgery and non-surgical modalities could be of benefit.

METHOD

Retrospective review of consecutive adult patients with SB NET treated at Imperial College Healthcare NHS Trust between 1 January 2010 and 31 December 2019. Data regarding clinicopathological characteristics, treatments, and disease trajectory were extracted and summarised. Overall and progression/recurrence-free survival were estimated at 5 and 10 years.

RESULTS

154 patients were identified, with a median age of 64 years (range 33-87); 135/154 (87.7%) had stage III/IV disease at diagnosis. Surgery was used in 125 individuals (81.2%), typically with either segmental small bowel resection (60.8%) or right hemicolectomy (33.6%) and mesenteric lymphadenectomy for the primary tumour. Systemic and/or liver-directed therapies were used in 126 (81.8%); 60 (47.6%) had more than one line of non-surgical treatment. Median follow-up was 67.2 months (range 3.1-310.4); overall survival at 5 and 10 years was 91.0% (95% CI: 84.9-94.7%) and 82.5% (95% CI: 72.9-88.9%), respectively. Imaging-based median progression-free survival was 42.7 months (95% CI: 24.7 to 72.4); 5-year progression-free survival was 63.4% (95% CI: 55.0-70.6%); 10-year progression-free survival was 18.7% (95% CI: 12.4-26.1). Nineteen patients (12.3%) reached 10 years follow-up without disease recurrence and therefore were considered cured.

CONCLUSIONS

Most patients with SB NET present in a metastasised stage. Multimodal treatment concepts may be associated with excellent clinical outcomes. Future work should explore optimal approaches to treatment sequencing and patient selection.

Primary Tumor Resection is Associated with Improved Disease-Specific Mortality in Patients with Stage IV Small Intestinal Neuroendocrine Tumors (NETs): A Comparison of Upfront Surgical Resection Versus a Watch and Wait Strategy in Two Specialist NET Centers

INTRODUCTION

Small intestinal neuroendocrine tumors (SI-NETs) often present with metastatic disease. An ongoing debate exists on whether to perform primary tumor resection (PTR) in patients with stage IV SI-NETs, without symptoms of the primary tumor and inoperable metastatic disease.

OBJECTIVE

The aim of this study was to compare a treatment strategy of upfront surgical resection versus a surveillance strategy of watch and wait.

METHODS

This was a retrospective cohort study of patients with stage IV SI-NETs at diagnosis, between 2000 and 2018, from two tertiary referral centers (Netherlands Cancer Institute [NKI] and Aintree University Hospital [AUH]) who had adopted contrasting treatment approaches: upfront surgical resection and watch and wait, respectively. Patients without symptoms related to the primary tumor were included. Multivariable intention-to-treat (ITT), per-protocol (PP), and instrumental variable (IV) analyses using 'institute' as an IV were performed to assess the influence of PTR on disease-specific mortality (DSM).

RESULTS

A total of 557 patients were identified, with 145 patients remaining after exclusion of stage I-III disease or symptoms of the primary tumor (93 from the NKI and 52 from AUH). The cohorts differed in performance status (PS; p = 0.006) and tumor grade (p < 0.001). PTR was independently associated with reduced DSM irrespective of statistical methods employed: ITT hazard ratio [HR] 0.60, p = 0.005; PP HR 0.58, p < 0.001; and IV HR 0.07, p = 0.019. Other factors associated with DSM were age, PS, high chromogranin A, and somatostatin analog treatment.

CONCLUSION

Taking advantage of contrasting institutional treatment strategies, this study identified PTR as an independent predictor of DSM. Future prospective studies should aim to validate these results.

Is Long-Term Survival in Metastases from Neuroendocrine Neoplasms Improved by Liver Resection?

Background and Objectives: Although many of the neuroendocrine neoplasms (NEN) have a typically prolonged natural history compared with other gastrointestinal tract cancers, at least 40% of patients develop liver metastases. This study aims to identify whether liver resection improves the overall survival of patients with liver metastases from NEN. Materials and Methods: We conducted a retrospective study at “Fundeni” Clinical Institute over a time period of 15 years; we thereby identified a series of 93 patients treated for NEN with liver metastases, which we further divided into 2 groups as follows: A (45 patients) had been subjected to liver resection complemented by systemic therapies, and B (48 patients) underwent systemic therapy alone. To reduce the patient selection bias we performed at first a propensity score matching. This was followed by a bootstrapping selection with Jackknife error correction, with the purpose of getting a statistically illustrative sample. Results: The overall survival of the matched virtual cohort under study was 41 months (95% CI 37–45). Group A virtual matched patients showed a higher survival rate (52 mo., 95% CI: 45–59) than B (31 mo., 95% CI: 27–35), (p < 0.001, Log-Rank test). Upon multivariate analysis, seven independent factors were identified to have an influence on survival: location (midgut) and primary tumor grading (G3), absence of concomitant LM, number (2–4), location (unilobar), grading (G3) of LM, and 25–50% hepatic involvement at the time of the metastatic disease diagnosis. Conclusions: Hepatic resection is nowadays the main treatment providing potential cure and prolonged survival, for patients with NEN when integrated in a multimodal strategy based on systemic therapy.

Postoperative morbidity and mortality after surgical resection of small bowel neuroendocrine neoplasms: A systematic review and meta-analysis

Although small bowel resection is generally considered a low risk gastrointestinal procedure, this might not be true for small bowel neuroendocrine neoplasms (SB-NEN) as a result of potential central mesenteric involvement. We aimed to determine the reported morbidity and mortality after resection of SB-NEN in the literature and assess the effect of hospital volume on postoperative morbidity and mortality. A systematic review was performed by searching MEDLINE and Embase in March 2021. All studies reporting morbidity and/or mortality after SB-NEN resection were included. Pooled proportions of overall morbidity (Clavien-Dindo I-IV), severe morbidity (Clavien-Dindo III-IV), 30-day mortality, 90-day mortality and in-hospital mortality were calculated, as well as the association with hospital volume (high volume defined as the fourth quartile). Thirteen studies were included, with a total of 1087 patients. Pooled proportions revealed an overall morbidity of 13% (95% confidence interval [CI] = 7%-24%, I²  = 90%), severe morbidity of 7% (95% CI = 4%-14%, I²  = 70%), 30-day mortality of 2% (95% CI = 1%-3%, I²  = 0%), 90-day mortality of2% (95% CI = 2%-4%, I²  = 35%) and in-hospital mortality of 1% (95% CI = 0%-2%, I²  = 0%). An annual hospital volume of nine or more resections was associated with lower overall and severe morbidity compared to lower volume: 10% vs 15% and 4% vs 9%, respectively. Thirty-day mortality was similar (2% vs 1%) and 90-day mortality was higher in high-volume hospitals: 4% vs 1%. This systematic review with meta-analyses showed severe morbidity of 7% and low mortality rates after resection of SB-NEN. The currently available literature suggests a certain impact of hospital volume on postoperative outcomes, although heterogeneity among the included studies constrains interpretation.

Outcomes of Simultaneous Resection of Small Bowel Neuroendocrine Tumors with Synchronous Liver Metastases

BACKGROUND

This study evaluated the short- and long-term outcomes of synchronous resection of liver metastases (LM) from small bowel neuroendocrine tumors (SB-NET).

METHODS

A retrospective review of patients undergoing resection for LMs from SB-NETs from January 1997 and December 2018 was performed.

RESULTS

There were 44 patients with synchronous SB-NET and LMs. Perioperative and 90-day mortality values were zero, and the morbidity rate was 27%. The median overall survival (OS) was 128.4 months (CI 95% 74.0-161.5 months) with 1-, 3-, 5-, and 10-year survival rates of 100%, 83%, 79%, and 60%, respectively. Not achieving surgical treatment for LM was the unique independent factor for survival (HR 6.50; CI 95% 1.54-27.28; p = 0.01) in patients with unresected LMs having OS and 10-year survival rates (42 months, 33%) versus patients undergoing liver resection (152 months, 66%)(p = 0.0008). The recurrence rate was 81.8% and associated with longer OS and 5-year survival rates when limited to the liver [223 months (61%) vs 94 months (87%)].

CONCLUSIONS

Simultaneous resection of SB-NETs with synchronous LMs was safe and associated with considerable long-term survival even in the presence of bilobar disease. However, recurrence after resection was common (81%) but associated with longer survival rates when limited to the liver.

Survival in Patients with Neuroendocrine Tumours of the Small Intestine: Nomogram Validation and Predictors of Survival

Neuroendocrine tumours of the small intestine (SI-NETs) are rare and heterogeneous. There is an unmet need for prognostication of disease course and to aid treatment strategies. A previously developed nomogram based on clinical and tumour characteristics aims to predict disease-specific survival (DSS) in patients with a SI-NET. We aimed to validate the nomogram and identify predictors of survival. Four hundred patients with a grade 1 or 2 SI-NET were included, between January 2000 and June 2016. Predicted 5- and 10-year survival was compared to actual DSS. Multivariable analysis identified predictors for actual DSS. We found that in low-, medium- and high-risk groups 5-year nomogram DSS vs. actual DSS was 0.86 vs. 0.82 (p < 0.001), 0.52 vs. 0.71 (p < 0.001) and 0.26 vs. 0.53 (p < 0.001), respectively. Ten-year nomogram DSS vs. actual DSS was 0.68 vs. 0.69 (p < 0.001), 0.40 vs. 0.50 (p < 0.001) and 0.20 vs. 0.35 (p < 0.001), respectively. Age, WHO-performance score of 2, Ki-67 index ≥10, unknown primary tumour, CgA > 6x ULN and elevated liver tests were identified as independent predictors for a worse DSS. This shows that the nomogram was able to differentiate, but underestimated DSS for patients with a SI-NET. Improvement of prognostication incorporating new emerging biomarkers is necessary to adequately estimate survival.